1. Field of the Invention
This invention relates to a method for producing pulp molded articles useful as, for example, packaging members such as containers and cushioning materials, etc.
2. Discussion of the Background
Plastics are used as general materials of packaging containers, for example, those with a lid and bottles, for their excellent molding properties and productivity. However, because plastic containers involve various problems associated with waste disposal, pulp molded containers formed by pulp molding have been attracting attention as substitutes for plastic containers. Pulp molded containers are not only easy to dispose of but economical because they can be manufactured by using regenerated paper.
Pulp molded articles having the above-described characteristics are produced by, for example as disclosed in Japanese Patent Laid-Open Publication No. 7-42100, depositing pulp fiber on the surface of a papermaking mold in a wet process, drying the resulting wet preform of deposited pulp fiber, and dehydrating and drying the preform by hot pressing from the upper and lower sides by use of a pair of porous molds, male and female, mating with each other.
However, where a preform is pressed from the upper and lower sides by a pair of porous male and female molds as in the above-described method, pressing onto the side wall of containers is uneven, resulting in poor surface properties unless the height of the containers is 60 mm or less and the draft angle, i.e., the angle formed between the draw line and the side wall of containers is 5xc2x0 or more. Therefore, it is difficult to control the wall thickness (basis weight and density). If a container has a relief design, etc. on it, the container will not be removed from the mold after pressing.
Thus, the above method is disadvantageous in that the possible shapes of molded articles are restricted, it is impossible to execute various designs on the surface of containers, and the surface properties are poor.
Japanese Patent Laid-Open Publication No. 7-223230 discloses a molding method which comprises pressing a molding material between an inner mold and an outer mold, wherein the inner mold is covered with a flexible film capable of expanding to form an contour that is substantially the same as the interior shape of an objective molded article and, at the same time, feeding a fluid from a fluid feed pipe to between the flexible film and the inner mold to inflate the flexible film. In this method, however, because a fluid is fed from one position between the flexible film and the inner mold, the pressing by the inflated flexible film onto the molding material is uneven, resulting in a failure to obtain molded articles uniform in wall thickness.
Accordingly, an object of the present invention is to provide a method for producing a pulp molded article by which a container having a complicated shape can be obtained regardless of a draft angle, etc. and which enables execution of various designs to provide a beautiful outer appearance with excellent surface smoothness; and to provide pulp molded articles.
The present invention has achieved the above object by providing a method for producing a pulp molded article comprising the steps of depositing pulp fiber on the outer surface of a papermaking core mold having a plurality of interconnecting paths connecting the outside and the inside to form a pulp deposited body, placing the pulp deposited body in a set of split molds, and then pressing the pulp deposited body for dehydration by a prescribed means.